An airbag device for a passenger seat in which a panel of an airbag that opposes a window when deployed is pleated and restrained by a strap, and when the airbag is deployed into an intermediate shape, the strap breaks and the airbag is deployed into a final shape is known from Patent Document 1 below.
Furthermore, an airbag device for a passenger seat in which part of an airbag that becomes a lower part on an occupant side when deployed is folded in two and stitched by control stitching, and when the internal pressure of the airbag increases to a predetermined value during the process of deployment the stitching part breaks and the airbag is deployed into a final shape is known from Patent Document 2 below.    Patent Document 1: Japanese Patent Application Laid-open No. 7-69149    Patent Document 2: Japanese Patent Application Laid-open No. 9-142238